The correct answer is B) Manufacture of toys. Here's why: HDP (High-Density Polyethylene): HDP is a rigid, strong, and versatile plastic with a wide range of applications. Let's analyze each option: A) Insulation of electric cables: LDPE (Low-Density Polyethylene) is more commonly used for electrical insulation due to its flexibility and electrical properties. B) Manufacture of toys: HDP is perfect for toys because of its durability, chemical resistance, and ability to be molded into various shapes. C) Submarine cable insulation: Submarine cables require specialized materials with extreme durability and water resistance. HDP is not typically used for this purpose. D) Producing extruded films: While HDP can be used for film extrusion, it is not the most common choice compared to other types of polyethylene. Key Point: HDP's properties make it ideal for manufacturing toys that need to withstand rough handling and maintain their shape.