Final answer:
The correct syntax for an if statement is option (a): if ($aVariable == 1). The statement should be followed by curly braces to define the code to execute if the condition is met.
Step-by-step explanation:
The correct syntax for an if statement in most programming languages, including PHP, is option (a):
if ($aVariable == 1). This syntax is used to execute code blocks based on the condition that $aVariable is equal to 1. The opening and closing curly braces {} should follow the if statement to define the scope of what should be executed if the condition is true:
if ($aVariable == 1) {
// Code to execute if the condition is true
}
Options b, c, and d do not represent the correct syntax. Option b mistakenly puts parentheses after the condition, and option c incorrectly places a semicolon directly after the condition which would end the statement prematurely. Option d is missing the parenthesis around the condition entirely, which is required in PHP and many other programming languages.