For Option 1: "The expression (x2+10x+25) cannot be simplified further" - This option is true because the expression is already in its simplest form, though it can be factored as (x+5)2. For Option 2: "The value of the variable in an equation which satisfies the equation is called a solution of the equation" - This option is true because the solution of an equation is defined as the value(s) of the variable(s) that make the equation true. For Option 3: The given expression 3+4×5 is a mathematical expression. So this is not true. Option 4: "Operations of multiplication can be done on mathematical expressions" - This option is true because multiplication is a valid operation that can be performed on mathematical expressions.