Final answer:
The charge of Sr in Sr(OH)2 is +2, as it balances the total -2 charge from the two hydroxide ions.
Step-by-step explanation:
The charge of strontium (Sr) in the compound strontium hydroxide, which is Sr(OH)2, can be determined by analyzing the charges of the other ions present in the compound. Hydroxide ions (OH-) each have a charge of -1. Since there are two hydroxide ions in the formula, this gives a total negative charge of -2. To balance this charge, the strontium ion must have a charge of +2 since the compound overall is neutral.
Therefore, the correct answer is: A. +2.