. Although the population of a certain salmon species in the Pleasant River S3 i7 ^0 b; ^) o1 g7 m, b
has not decreased in the last five years, the average size of adult female " R9 y5 z6 m2 e) f8 K" n9 u
salmon of that species in the river has decreased significantly in this time.1 y f2 y; s- r0 ]7 s
The latter fact indicates that the population of this species is ultimately
* g! k# ^' @0 [! M$ Lendangered, since small fish of a given species lay far fewer eggs than
" ]1 s! ]5 z# b9 W+ W2 M: j, `do large fish of the same species., P7 Z1 ]# q/ R( V, G/ M7 \! Y
Which of the following is an assumption on which the argument depends?
( M a; w* A, p% v# \6 E A Excluding fish of the salmon species, the average size of fish in the / v2 Q: Y4 z0 \6 I. z
Pleasant River has increased over the past five years. ! d7 O2 X6 p+ m1 F0 K5 n/ p
B The largest adult female salmon living in the Pleasant River five
2 D* @3 T' Z9 \9 u- R years ago were significantly larger than the largest adult female 2 }$ t/ N4 Y( Z+ t4 ? g5 `2 q
salmon living there now.
8 B% n& F+ z h# g& Z* y C Smaller salmon are not an easier prey for salmon predators than are # D. \1 @3 B" t. B2 F3 a. b
larger salmon. . |& e' r& M: _# g
D The total number of eggs laid each year by salmon of the species
( u$ S+ V: X! M5 X in the Pleasant River has not varied significantly over the past five
! ?/ C- r) [/ B5 Q% k" i/ N4 M years. : A L. M/ i6 E- c3 `
E The proportion of the eggs laid by small salmon of the species that
. a8 O# b6 U" Y, t( Q8 m! z1 e% L hatch into fish that reach reproductive maturity is not significantly
9 {$ k$ L/ }6 S, S* \/ Q5 n greater than that of the eggs laid by large salmon of the species.
3 _- q1 k: p* g1 X# E答案E |