Logic of a solution: *Male dogs use pheromones in urine to mark their territory. Pheromones are a sub-category of semiochemicals. Male dogs use semiochemicals in urine to mark their territory.*
*(D)*
The original question: *Male dogs use_ in urine to mark their territory.
Options:
- (A) ammonia
- (B) Chemical energy
- (C) proteins
- (D) semiochemicals
- (E) animals
- (F) heat produced
- (G) nitric oxide
- (H) They have thick fur*

Logic of a solution: *Urine is the liquid waste product of the body that is excreted by the urinary system. Mammals excrete urea in the watery form of urine . Urea is a waste product of the body that is excreted by the urinary system.*
*(E)*
The original question: *What is a waste product of the body that is excreted by the urinary system?
Options:
- (A) potash
- (B) food
- (C) CO 2
- (D) sugar
- (E) urea
- (F) liquid
- (G) H 2 O
- (H) sulfur*

Logic of a solution: *Most salamanders use their sense of smell to find a mate. Olfaction is the sense of smell. Most salamanders use olfaction to find a mate.*
*(A)*
The original question:
*What do most salamanders use to find a mate?
Options:
- (A) olfaction
- (B) sound
- (C) seduction
- (D) fur and fat
- (E) heat energy
- (F) air
- (G) environment
- (H) water*