Which one of the following differential equations has a periodic solution?

The order and degree of the differential equation $${y^2} = 4a(x - a)$$, where 'a' is an arbitrary constant, are respectively

What is the solution of $$(1 + 2x)dy - (1 - 2y)dx = 0$$ ?

What are the order and degree, respectively, of the differential equation $$\left( {{{{d^3}y} \over {d{x^3}}}} \right) = {y^4} + {\left( {{{dy} \over {dx}}} \right)^5}$$ ?