Aspring tide occurs during which of the following conditions? a: ) the earth is aligned with the moon and sun. b: ) the earth is aligned with the sun only. c: ) the earth is aligned with the moon only. d: ) the moon-earth and sun-earth alignments are perpendicular.

Spring tides occur when the Earth, sun and moon are aligned. Despite its name spring tides have nothing to do with the Spring season. It was derived from the concept of "springing-forth" . They occur at twice each lunar month, bringing higher tides during high tide and lower tides during low tide. 

  

Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example :   8+b8+b  or  a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1:   x=4+2x=4+2  , [here, we can observe that the variable is present only on one side of the equation].example 2:   2x+3=x+42x+3=x+4  , [here, we can observe that the variables are present on both side of the equation].