During the day in Lake Constance, the zooplankton D. hyaline departs for the depths where food is scarce and the water cold. D. galeata remains near the warm surface where food is abundant. Even though D. galeata grows and reproduces much faster, its population is often outnumbered by D. hyaline.

Which of the following, if true, most helps to resolve the apparent paradox?


A. The number of species of zooplankton living at the bottom of the lake is twice that of species living at the surface.

B. Predators of zooplankton, such as whitefish and perch, live and feed near the surface of the lake during the day.

C. In order to make the most of scarce food resources, D.hyaline matures more slowly than D. galeata.

D. galeata clusters under vegetation during the hottest part of the day to avoid the Sun’s rays.

E. galeata produces twice as many offspring per individual in any given period of time as does D. hyaline.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Clear B man.good question this.

B and C are the main contenders

B - Says why D.g population is less

C - Restates what is already given in the passage(D.g reproduces faster).Hence incorrect.

Even though D. galeata grows and reproduces much faster, its population is often outnumbered by D. hyaline.

Option B says Predators of Zooplankton D. zylen live and feed near surface during the day. Predators are feeding on D.Z. not on D.G.
Then how would population of D.G. reduce?

Please clear my confusion.

Two possible explanations:

1. No. of eggs laid / offsprings produced by DH >DG:
Ans choice E is opposite to this info.

2. Life-span of DH >DG: Ans choice B.

Hence, IMO, Ans is choice B

Posted from my mobile device