Although many teenagers still visit movie theaters, some economically conscientious parents remind their kids that monthly in-home streaming video services subscribing cost about the same as a movie ticket.

A. some economically conscientious parents remind their kids that monthly in-home streaming video services subscribing cost about the same as a movie ticket. -> "Subscribing cost" is incorrect. We need to use "subscription cost" another error, we need to compare "in-home streaming video subscription cost" to "movie ticket cost"

B. some economically conscientious parents remind them that subscribing to a monthly in-home streaming video service costs about the same as a movie ticket.-> The biggest issue here is "them". Parents need to refer to "their kids. Another issue, we need to compare "in-home streaming video subscription cost" to "movie ticket cost"

C. some economically conscientious parents remind their kids that a monthly in-home streaming video service subscription costs about the same as movie tickets.->we need to compare "in-home streaming video subscription cost" to "movie ticket cost"

D. some economically conscientious parents remind their kids that a monthly in-home streaming video service subscription costs about the same as a movie ticket does-> Comparison issue is resolved. And, there is no further error introduced. Let's keep it.

E. some economically conscious parents remind their kids that monthly in-home streaming video services costs about the same as movie tickets do. -> "in-home streaming video services costs" is incorrect. We need "subscription".

So, I think D.

Split 1 - 'them' and 'their kids'
'their kids' is much clearer than 'them' in the clause 'parents remind .... that....'
=> eliminate B

Split 2 - Subject - Verb agreement
+ Choice A - 'video services subscribing' (singular noun) + 'cost' (plural verb) => incorrect
+ Choice C - 'video service subscription' (singular noun) + 'costs' (singular verb) => okay
+ Choice D - 'video service subscription' (singular) + 'costs' (singular) => okay
+ Choice E - 'video services' (plural) + 'costs' (singular) => incorrect
=> eliminate A and E

Split 3 - comparison entities

+ Choice C - 'video service subscription' (singular) and 'movies tickets' (plural)
+ Choice D - 'video service subscription' (singular) and 'a movie ticket' (singular)

=> Choice D is better

Ans: D

Analysis:
Cost/Costs
The video subscription is singular so we need singular 'costs'

Comparison:
We are comparing the cost of video service subscription to the cost of a movie ticket in theater. So we need to look for answer choice that compare the costs correctly.

A. some economically conscientious parents remind their kids that monthly in-home streaming video services subscribing cost about the same as a movie ticket.- INCORRECT
The cost we are discussing is not cost to subscribe, but actual subscription cost and also we need singular 'costs'

B. some economically conscientious parents remind them that subscribing to a monthly in-home streaming video service costs about the same as a movie ticket. INCORRECT
'Them' do not have clear antecedant. 'remind their kids' is a better choice.

C. some economically conscientious parents remind their kids that a monthly in-home streaming video service subscription costs about the same as movie tickets - INCORRECT
Subscription is singular and its compared to movie tickets which is plural.

D. some economically conscientious parents remind their kids that a monthly in-home streaming video service subscription costs about the same as a movie ticket does - CORRECT

E. some economically conscious parents remind their kids that monthly in-home streaming video services costs about the same as movie tickets do. - INCORRECT
services is plural , so we need plural 'costs'
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