IMO E
(1) We know one of the investors owns 1/4. All this tells us is that all other investors own 3/4 combine. It doesn't tell us anything about the price of the stock. For example. 1/4 of the stock is worth $20K, which means answer would be $80K. If 1/4 of the stock is worth $100K, then total value is $400K. NOT SUFFICIENT. Eliminate A and D.
(2) ANOTHER (different) investor owns stock worth $16K. Alone this doesn't tell us how much of the total stock this investor owns. For example, if this investor owned 100% of the stock, answer would be $16K. If he owned 50% of the stock, answer would be $32K. NOT SUFFICIENT. Eliminate B.
(1) + (2) Together
Key point here is the investor in statement 1 is not the same as the one in statement 2. I think this still doesn't tell us the total value of the stock. Let the investor in statement 1 be A and investor in statement 2 be B.
This means A owns 1/4 of the total value (say X) and B owns $16K worth of stock. If we assume there are no other investors other than A and B, this means 3.4*X = 16,000 -> X = $21,333.33K
But it may be the case that there are investors other than A and B (for simplicity let's say C). Now let's say the remaining 3/4 that investor A does not own is split equally among B and C. So B owns 3/8 of X which is equal to $16,000. In this case, X = 42,666.67.
So together we are still able to make cases that are not unique. NOT SUFFICIENT. Hence I think E.
(Pls let me know if the rationale is not on the right track)